Portland cement

The production of Portland cements with a reduced clinker content corresponds to the strategy of decarbonization of building materials, aimed at reducing the negative impact on the environment and climate changes. This direction of development of the cement industry requires the use of more mineral additives. The application of waste-derived materials as the main non-clinker component is promising. The advantage of using wet-handled coal bottom ash is its pozzolanic effect and high grindability, but the main disadvantage is increased moisture.

The work investigated the possibility of using construction waste such as asbestos-cement slate, glass, brick and concrete as aggregates in mixtures for the base layers of road pavement made using cold recycling technology. For this purpose, 17 mixture compositions were designed and studied - the control composition and 4 series of compositions, in which the milled fine-grained asphalt concrete was partially replaced by crushed asbestos-cement slate, glass, brick and concrete in an amount of 5-20 wt.%. All studied compositions contained 3% Portland cement and 3% water.

The regularities of the synthesis of calcium hydrosilicates of tobermorite composition in the system "amorphous silica – calcium hydroxide – water" were investigated. The effect of calcium hydrosilicates additive on the hydration processes of Portland cement and the nature of changes in the strength of cement stone at different stages of its hardening was studied.

The article presents the results of studies of the influence of technological factors (clinker factor of cements, grain composition of aggregates, cement consumption in concrete, modifier additives) on technical and environmental indicators of concrete efficiency. It has been shown that in combination, the parameters of clinker and CO2 intensities characterize the clinker efficiency of concrete, which can be improved by replacing part of the clinker in mixed cements with active mineral additives.

Nowadays conventional binding material for the construction sector is Portland cement. Portland cement consists mainly of high-energy intensive with a significant carbon footprint Portland cement clinker. Reduction of clinker content in binding materials becomes the utmost priority for scientists in the field, it is reflected in manufacturers’ Sustainability Road Maps.

The article contains research materials on solving the problem of utilization of waste phosphogypsum by using it in the layers of the road base. For this purpose, composite mixtures based on raw dump phosphogypsum were prepared. The composition of the composite mixtures was optimized to maximize the phosphogypsum content. The phosphogypsum was stabilized with ground granulated blast furnace slag and Portland cement.

The influence of vibro-activated lime additive on the hydration processes of Portland cement and the nature of changes in the strength of cement stone at different stages of its hardening were studied. It was established that long-term storage of vibro-activated lime in a wet state does not weaken its properties as a modifying additive.

This article describes the classification of cationic bitumen emulsions according to "reactivity" and breaking behaviour characteristics. The methods of researching the characteristics of breaking behaviour for bitumen emulsions of different "reactivity" in accordance with European and Ukrainian regulatory documents are presented. Available possible emulsifiers in Ukraine for over-stabilised bitumen emulsions are given with a description of road technology where they can be applied.

The article presents the peculiarities of obtaining superplasticized cementitious systems "Portland cement – fly ash - superplasticizer" to find a rational provision of the given construction and technical properties of concrete. It was studied the physico-chemical peculiarities of the hydration processes of superplasticized cementitious systems. There were solved problems of directional formation of the microstructure of cement stone.

The article considers the possibility of using wastepaper sludge ash (WSA) as a soil reinforcement material for the construction of layers of road wear. Loamy sand, sandy loam, silty clay loam, silty clay were chosen as soils for strengthening. The maximum density of the soil skeleton at optimum humidity was established by the method of Proctor. Wastepaper sludge ash and Portland cement grade 400 were used separately for soil strengthening.